The present invention relates to a wrapping machine for wrapping five surfaces of an article except the bottom thereof, and a method to do the same. More particularly, the machine and the method of the present invention are useful for wrapping an article having a variable length such as a bundle of lumber, plywood or the like, or a pile of other products, or a single article.
A very significant proportion of lumber and construction panels are currently shipped and stored in bundles or piles wrapped in a waterproof envelope in order to provide a protection against alterations due to weather conditions and stabilise the humidity level.
Traditionally, the placement and folding of the wrapper sheet has mostly been carried-out in a semi-automatic fashion, a web like material being supplied from a material roll positioned above the article to be wrapped. Also, prefabricated plastic envelopes (bags) are currently used to speed-up the wrapping operation. The bag is generally installed from the top of the bundle, thus protecting the top and the sides of the bundle, while allowing some air circulation through the bottom. In this latter case, the envelope is manually secured to the bundle by stapling into the wood pieces. In this case, the operation is still quite expensive since extensive manpower is still required and the cost of the envelopes is relatively high.
Many automated solutions have been proposed in the prior art to wrap palletised articles In a plastic film or web. However, most of these solutions perform the wrapping operation by rotating a narrow plastic film roll around the load on a spiral path. Such techniques are not practical for elongate articles such as lumber bundles and do not provide automatic installation of a top web member nor yield a neat result.
It is also known in the art to use an automated system to slide a bundle of lumber into a bag that is then manually closed and sealed at one end. The economic performance of that process is still limited since expensive large prefabricated bags are required in a wide range of sizes, thus also resulting in inventory concerns.
Also known in the art, there is the U.S. Pat. No. 5,657,608 which discloses a fully automated method for wrapping a parallelepipedly shaped article such as a bundle of lumber, using a web like material supplied from a roll located over the article. The wrapper material is dispensed and folded around the article in a continuous process by the relative movements of a backing means and the article, plus the movement of the article with respect to spring loaded rollers as folding members. The principal embodiments of that invention as described show several limitations and drawbacks, The main drawback is certainly the fact that the process must be continuous, so that a new set-up is required after each time an incoming article does not require wrapping, that situation occurring frequently since only a part of lumber shipments must be wrapped. It shall also be noted that tho folding caused by the rollers is not precisely controlled and will generally yield a poor looking result and very visible folding lines on the long sides of the article. That poor looking result is also subject to be emphasised by the presence of static electricity in plastic based wrapper material. Moreover, it is worth indicating that it is generally not acceptable to apply adhesive all over the article to hold the web in place. Another obvious limitation of that process is that the article is moved back and forth a few times to complete the wrapping. Since the contemplated articles are long and heavy, a lot of time and energy is required.
The present invention is directed to a wrapping machine and a related method that overcome the above-mentioned drawbacks.
In accordance with the present invention, there is provided a wrapping machine for wrapping an article located in a wrapping area, comprising:
web delivering means for delivering a web;
first clamping means for clamping a first end of the web extending from the web delivering means;
first moving means for moving the first clamping means;
cutting means for cutting the web extending from the web delivering means and therefor providing a web piece for wrapping the article;
second clamping means for clamping a second end of the web piece that is a free end opposite to said first end;
second moving means for moving the second clamping means;
fastening means for fastening the web piece on the article; and
a controller for controlling the web delivering means, the first and second clamping means, the first and second moving means, the cutting means, and the fastening means following a predetermined sequencing program in such a way that, in operation, the web piece is moved and put down over the article by means of the first and second clamping means and the first and second moving means, and is fastened to the article by means of the fastening means.
In accordance with the present invention, there is also provided a method for wrapping an article, comprising the steps of:
a) delivering a web by means of a web delivering means;
b) clamping a first end of the web extending from the web delivering means by means of a first clamping means;
c) moving said first end away from the delivering means by means of the first clamping means;
d) after stop (c), cutting the web extending from the web delivering means and therefor providing a web piece for wrapping the article;
e) clamping a second end of the web piece that is a free end opposite to said first end by means of a second clamping means;
f) moving and putting down the web piece over the article by means of the first and second clamping means; and
g) after step (f), fastening the web piece on the article.
Advantageously, the machine and the method of the present invention provide an automatic adjustment of the length of the article.
According the method and the machine of the invention, it is not necessary to move the article during its wrapping which is very advantageous for heavy article.
The present invention has also the advantage of providing a fully automated machine with a very high level at control and accuracy.
A preferred embodiment of the invention has a further advantage of providing a clean and neat appearance of the wrapped article with the web folded only at the ends of the article and no apparent folding line.
The invention and its advantages will be better understood after reading the non restrictive description of a preferred embodiment of the present invention. This description is given with reference to the appended drawings.